Small satellite propulsion systems generally must be small in size while generating high specific impulse with limited power. Such systems typically produce impulse bits on the order of 10−6 N-s while using very small propellant flow rates controlled by microvalves.
Propulsion systems are known that pass a gas propellant through an expansion slot with heated walls. The gas molecules become heated as they collide with the walls. The heated molecules have increased energy and therefore pass through the expansion slot with greater speed producing greater thrust and specific impulse.
Electrothermal propulsion systems are also known in which a pair of electrodes are used to produce a plasma discharge in a cavity. When a propellant is introduced into the cavity, the discharge couples energy into the propellant and localized stochastic heating results raising the enthalpy of the propellant.
Electrostatic or ion propulsion systems apply a static electric force (Coulomb Force) to a propellant including charged particles. Magnetic or electromagnetic fields have also been used to increase the flow of a charged propellant (applying a Lorentz Force). Such applications have been used in combination with heating techniques to further increase thrust in a rocket engine. See for example U.S. Pat. No. 6,334,302.
As exploration and other space applications progress propulsion systems are desired that produce greater thrust or specific impulse while maintaining a small payload, form factor, or power requirement. In addition, propulsion systems are desired that produce sufficient thrust or specific impulse while reducing the payload, form factor, or power required. These and/or other objectives can be met by embodiments of the subject invention as further described below.